Refrigerator and/or freezer

ABSTRACT

The present invention relates to a refrigerator and/or freezer, comprising a liquefier, an evaporator and a compressor, wherein the refrigerator and/or freezer includes means by which a pressure compensation between liquefier and evaporator is prevented or slowed down during the standstill of the compressor, and that the refrigerator and/or freezer includes a means for effecting the compressor start-up, wherein the means for effecting the compressor start-up comprise means for increasing the starting torque of the compressor and/or means for increasing the starting current of the compressor motor and/or means which ensure that the crank shaft of the compressor stops in a preferred position after shutting off the compressor motor, and/or means for the at least partial pressure compensation between the pressure side and the suction side of the compressor and/or means for reducing the initially required starting torque.

The present invention relates to a refrigerator and/or freezer, comprising a liquefier, an evaporator and a compressor.

Such refrigerators and/or freezers are known in a number of different embodiments. The refrigeration circuits of the appliances include an evaporator, in which the refrigerant is evaporated by absorbing heat from the space to be cooled. The evaporated refrigerant then is compressed in the compressor and is then supplied to the liquefier, in which it is liquefied by releasing heat to the surroundings. The refrigerant liquefied in this way is expanded in a throttle means and then again supplied to the evaporator.

To achieve an increase in efficiency of the refrigeration circuit and an energetic optimization of the refrigerator and/or freezer, the pressure compensation between the pressure side and the suction side during the downtime of the compressor can for instance be prevented by a shut-off valve between liquefier and evaporator. The use of such shut-off valve, however, involves the problem that due to the pressure compensation prevented by the shut-off valve, the compressor must start against a comparatively high pressure in the liquefier.

It is the object underlying the present invention to develop a refrigerator and/or freezer as mentioned above such that a safe start-up of the compressor also is ensured at back pressure.

This object is solved by a refrigerator and/or freezer with the features of claim 1. Accordingly, it is provided that the refrigerator and/or freezer has a means for effecting the compressor start-up, wherein the means for effecting the compressor start-up includes one or more of the means mentioned below:

(i) means for increasing the starting torque of the compressor and/or

(ii) means for increasing the starting current of the compressor motor and/or

(iii) means for stopping the compressor such that upon shutting off the compressor motor the crank shaft of the compressor stops in a preferred position, from which the compressor start-up also is possible at back pressure, and/or

(iv) means for the at least partial pressure compensation between the pressure side and the suction side of the compressor, and/or

(v) means for reducing the initially required starting torque.

As a result of said means, which can be implemented individually or also in combination, it is possible to reliably ensure that the compressor also starts at back pressure, which accordingly provides for a particularly reliable operation of the refrigeration circuit and thus of the appliance.

In accordance with the invention, it is thus conceivable that the starting torque of the compressor is increased to overcome said pressure difference between the suction side and the pressure side of the compressor. This is also meant to include the case that the compressor motor is supported by means which generate a supporting moment, which acts in the direction of the torque applied by the motor. These means can for instance be a spring which is tensioned when the compressor is at standstill.

In one possible embodiment of the invention it is thus provided that the means for increasing the starting torque of the compressor comprise at least one spring or elastic element, which is configured and arranged such that it is tensioned in the condition in which the compressor is at standstill and in the tensioned condition exerts a moment supporting the compressor start-up. It is conceivable, for instance, to provide an eccentric moving upon operation of the compressor, which ensures that the spring or the elastic element is tensioned when the compressor is at standstill.

It is also possible to provide an intelligent electronic starting device, which with the existing starting torque of the compressor ensures a safe starting at back pressure. This allows to briefly provide a higher starting current than is permitted by the motor protection.

It is likewise possible to stop the compressor such that the same stops in a preferred position, in which starting at back pressure is possible. Alternatively or in addition it can be provided that a partial pressure compensation is performed before starting the compressor, in order to reduce the pressure against which the compressor must start.

It is possible, for instance, to reduce the pressure level at the pressure side via a bypass connecting the suction side with the pressure side, so that the back pressure, against which the compressor must start, is reduced.

It is also possible to reduce the initially required starting torque. This can be effected, for instance, in that the compressor motor initially need not apply the full moment required for starting the compressor. This means that the motor starts against a reduced moment and must apply the full moment only at a later date.

In one possible aspect of the invention it is provided that the compressor motor includes a shaft or that a shaft is connected with the compressor motor, which has at least two separate shaft portions, and that the means for reducing the initially required starting torque comprise a spring or a deformable power transmission element, which is connected with the two separate shaft portions such that a rotation of one shaft portion effects a rotation of the other shaft portion via the spring or the power transmission element. The spring or the deformable power transmission element acts as a coupling between the two ends of the shaft portions. When one of the shaft portions is moved by the motor, the spring or the deformable element permits a relative movement (slip) between the two shaft portions, which results in the fact that the initially required starting torque is reduced. For instance, the spring can be arranged such that it encloses the ends of the shaft portions and furthermore extends in the region between the shaft portions.

In a further aspect of the invention it is provided that the appliance includes a testing means for checking the starting behavior of the compressor, which is configured such that it detects whether the compressor is starting properly, and that actuating means are provided, which are activated by the means for effecting the compressor start-up with the means (i) and/or (ii) and/or (iv), when it is detected by means of the testing means that the compressor has not started.

In this aspect of the invention it can be provided that the starting torque of the compressor and/or the starting current of the compressor motor only are increased and/or the at least partial pressure compensation only is performed when it is detected by means of the testing means that the compressor has not started as desired. If this is the case, the starting torque or the starting current can be increased or an at least partial pressure compensation can be performed, in order to provide for a start-up of the compressor.

The actuating means can form part of the testing means.

In a further aspect of the invention it is provided that the actuating means are configured such that they are activated by the means for effecting the compressor start-up with the means (i) and/or (ii) and/or (iv) only for a period, until a proper start-up of the compressor is detected by means of the testing means.

In this embodiment of the invention, said means must only be activated for a period, until it is detected that the compressor has started. Subsequently, the partial pressure compensation can be prevented e.g. by closing a valve in a bypass line, so that the desired build-up of pressure by the compressor is possible.

In a further aspect of the invention it is provided that the means for the at least partial pressure compensation between the pressure side and the suction side of the compressor comprise a bypass line, which can be located inside or also outside the compressor housing.

This bypass line can include a pressure compensation valve.

Thus, it is possible, for instance, to provide a bypass line around the compressor, in which a valve is disposed, which is closed in normal operation of the compressor, so that a futile circular flow is prevented, and which is temporarily opened when it is detected that a start-up of the compressor is not possible at back pressure. In this case, the valve can be opened, which preferably is effected only for such a period and to such an extent until it is detected by means of the testing means that the compressor is running properly.

It is also conceivable that inside the compressor a bypass is provided, which connects the pressure side of the compressor with the suction side of the compressor and which likewise leads to the fact that the back pressure is reduced on the pressure side. This bypass can of course also include a pressure compensation valve, by means of which an at least partial pressure compensation is possible. Preferably, this pressure compensation valve also is opened for such a period and to such an extent until it is detected by means of the testing means that the compressor now has started properly.

Further details and advantages of the invention will be explained in detail with reference to an embodiment illustrated below:

In accordance with the embodiment described below, the refrigerator and/or freezer of the invention includes a compressor, a liquefier provided downstream of the same, and a capillary in which the liquefied refrigerant is expanded. The same then is introduced into the evaporator, whose outlet is connected with the inlet of the compressor.

To prevent a pressure compensation between the pressure side and the suction side during the downtime of the compressor, an on/off valve is provided, which is located between liquefier and evaporator, preferably in a region between the liquefier and said capillary. While the compressor is at standstill, the valve is closed, which leads to the fact that a comparatively high pressure exists in the liquefier and hence also on the pressure side of the compressor.

To ensure a smooth and reliable start-up of the compressor after its downtime, the refrigerator and/or freezer of the invention includes means for increasing the starting torque of the compressor, which are configured such that the starting torque is increased to such an extent that the corresponding pressure difference is overcome and the compressor starts. This can also be determined by a suitable testing means. It can be provided that actuating means are provided, which effect a corresponding increase of the starting torque. It is conceivable that the actuating means are configured such that they perform an increase of the starting torque stepwise or continuously, until the desired start-up of the compressor is detected by means of the testing means.

Alternatively or in addition, it can be provided that the appliance includes an intelligent electronic starting device, by means of which a safe starting of the compressor should be made possible with the already existing starting torque of the compressor. The same allows to briefly provide a higher starting current than is actually permitted by the motor protection. Here, it can also be provided that a testing means checks whether the compressor has started, and that the actuating means increase the starting current stepwise or continuously until the start-up of the compressor is detected.

It is also possible to always stop the compressor in a position in which the crank shaft is in a preferred position, from which a reliable starting also is possible at back pressure. Here, it can also be provided that subsequent to the downtime of the compressor, a testing means checks whether the compressor has started, and if this is not the case, it can for instance be provided that one of the above-mentioned measures and/or also a partial pressure compensation is performed, in order to enable the start-up.

It is furthermore conceivable that with the refrigeration circuit shut off a bypass with an additional pressure compensation valve inside the compressor prevents that the compressor must start against an excessive back pressure. It is conceivable that this additional pressure compensation valve is closed in normal operation of the compressor, in order to prevent a circular flow and hence increase the efficiency of the compression, and is only opened when this is necessary to reduce the back pressure of the compressor. 

1. A refrigerator and/or freezer comprising a liquefier, an evaporator and a compressor, wherein the refrigerator and/or freezer includes means by which a pressure compensation between liquefier and evaporator is prevented or slowed down while the compressor is at standstill, the refrigerator and/or freezer includes a means for effecting the compressor start-up, the means for effecting the compressor start-up comprise (i) means for increasing the starting torque of the compressor and/or (ii) means for increasing the starting current of the compressor motor and/or (iii) means which ensure that the crank shaft of the compressor stops in a preferred position upon shutting off the compressor motor and/or (iv) means for the at least partial pressure compensation between the pressure side and the suction side of the compressor and/or (v) means for reducing the initially required starting torque.
 2. The refrigerator and/or freezer according to claim 1, where testing means is provided for checking the starting behavior of the compressor, which is configured such that it detects whether the compressor starts, and actuating means are provided, which are activated by the means for effecting the compressor start-up with the means (i) and/or (ii) and/or (iv), when it is detected by the testing means that the compressor has not started.
 3. The refrigerator and/or freezer according to claim 2, wherein the actuating means form part of the testing means.
 4. The refrigerator and/or freezer according to claim 1, wherein the actuating means are configured such that they are only activated by the means for effecting the compressor start-up with the means (i) and/or (ii) and/or (iv) for a period until a proper start-up of the compressor is detected by the testing means.
 5. The refrigerator and/or freezer according to claim 1, wherein the means for the at least partial pressure compensation between the pressure side and the suction side of the compressor comprise a bypass line which extends inside or outside the compressor.
 6. The refrigerator and/or freezer according to claim 5, wherein a pressure compensation valve is disposed in the bypass line.
 7. The refrigerator and/or freezer according to claim 6, wherein the actuating means are configured such that they open the pressure compensation valve for a period until the start-up of the compressor is detected by means of the testing means.
 8. The refrigerator and/or freezer according to claim 1, wherein the means for increasing the starting torque of the compressor comprise at least one spring or elastic element, which is configured and arranged such that it is tensioned in the condition in which the compressor is at standstill and in the tensioned condition exerts a moment supporting the compressor start-up.
 9. The refrigerator and/or freezer according to claim 1, wherein the compressor motor includes a shaft or a shaft is connected with the compressor motor, which has at least two separate shaft portions, and the means for reducing the initially required starting torque comprise a spring or a deformable power transmission element, which is connected with the two separate shaft portions such that a rotation of one shaft portion effects a rotation of the other shaft portion via the spring or via the power transmission element.
 10. the refrigerator and/or freezer according to claim 2, wherein the actuating means are configured such that they are only activated by the means for effecting the compressor start-up with the means (i) and/or (ii) and/or (iv) for a period until a proper start-up of the compressor is detected by the testing means.
 11. the refrigerator and/or freezer according to claim 3, wherein the actuating means are configured such that they are only activated by the means for effecting the compressor start-up with the means (i) and/or (ii) and/or (iv) for a period until a proper start-up of the compressor is detected by the testing means.
 12. The refrigerator and/or freezer according to claim 11, wherein the means for the at least partial pressure compensation between the pressure side and the suction side of the compressor comprise a bypass line which extends inside or outside the compressor.
 13. The refrigerator and/or freezer according to claim 10, wherein the means for the at least partial pressure compensation between the pressure side and the suction side of the compressor comprise a bypass line which extends inside or outside the compressor.
 14. The refrigerator and/or freezer according to claim 2, wherein the means for the at least partial pressure compensation between the pressure side and the suction side of the compressor comprise a bypass line which extends inside or outside the compressor.
 15. The refrigerator and/or freezer according to claim 3, wherein the means for the at least partial pressure compensation between the pressure side and the suction side of the compressor comprise a bypass line which extends inside or outside the compressor.
 16. The refrigerator and/or freezer according to claim 4, wherein the means for the at least partial pressure compensation between the pressure side and the suction side of the compressor comprise a bypass line which extends inside or outside the compressor.
 17. The refrigerator and/or freezer according to claim 16, wherein a pressure compensation valve is disposed in the bypass line.
 18. The refrigerator and/or freezer according to claim 15, wherein a pressure compensation valve is disposed in the bypass line.
 19. The refrigerator and/or freezer according to claim 14, wherein a pressure compensation valve is disposed in the bypass line.
 20. The refrigerator and/or freezer according to claim 13, wherein a pressure compensation valve is disposed in the bypass line. 